Next → Post Test: The Pythagorean Theorem and Volume

The U.S Census Brureau has a population clock on the internet.On a recent day the United States population was listed as 310,763

goldfiish [28.3K]

Three hundred ten million, seven hundred sixty three thousand, one hundred thirty six

6 0

3 years ago

The following function represents the profit P(n), in dollars, that a concert promoter makes by selling tickets for n dollars ea

Gre4nikov [31]

A) zeroes

P(n) = -250 n^2 + 2500n - 5250

Extract common factor:

P(n)= -250 (n^2 - 10n + 21)

Factor (find two numbers that sum -10 and its product is 21)

P(n) = -250(n - 3)(n - 7)

Zeroes ==> n - 3 = 0 or n -7 = 0
Then n = 3 and n = 7 are the zeros.

They rerpesent that if the promoter sells tickets at 3 or 7 dollars the profit is zero.

B) Maximum profit

Completion of squares

n^2 - 10n + 21 = n^2 - 10n + 25 - 4 = (n^2 - 10n+ 25) - 4 = (n - 5)^2 - 4

P(n) = - 250[(n-5)^2 -4] = -250(n-5)^2 + 1000

Maximum ==> - 250 (n - 5)^2 = 0 ==> n = 5 and P(5) = 1000

Maximum profit =1000 at n = 5

C) Axis of symmetry

Vertex = (h,k) when the equation is in the form A(n-h)^2 + k

Comparing A(n-h)^2 + k with - 250(n - 5)^2 + 1000

Vertex = (5, 1000) and the symmetry axis is n = 5.

8 0

3 years ago

A researcher records the repair cost for 8 randomly selected washers. A sample mean of $60.46 and standard deviation of $18.36 a

Anuta_ua [19.1K]

Answer:

The critical value is T = 1.895.

The 90% confidence interval for the mean repair cost for the washers is between $48.159 and $72.761

Step-by-step explanation:

We have the standard deviation for the sample, so we use the t-distribution.

The first step to solve this problem is finding how many degrees of freedom, we have. This is the sample size subtracted by 1. So

df = 8 - 1 = 6

90% confidence interval

Now, we have to find a value of T, which is found looking at the t table, with 6 degrees of freedom(y-axis) and a confidence level of $1 - \frac{1 - 0.9}{2} = 0.95$ . So we have T = 1.895, which is the critical value.

The margin of error is:

$M = T\frac{s}{\sqrt{n}} = 1.895\frac{18.36}{\sqrt{8}} = 12.301$

In which s is the standard deviation of the sample and n is the size of the sample.

The lower end of the interval is the sample mean subtracted by M. So it is 60.46 - 12.301 = $48.159

The upper end of the interval is the sample mean added to M. So it is 60.46 + 12.301 = $72.761

The 90% confidence interval for the mean repair cost for the washers is between $48.159 and $72.761

8 0

3 years ago

I forgot how to do this, can someone help me-

Artyom0805 [142]

Step-by-step explanation:

1) x/20 = -9

By cross multiplication,

x = -180

2) -168 = -14k

k = -168/-14

k = 12

3) -5m = -50

m = 10

4) -320 = -20n

n = 16

5) -4 = x - 5

x = 1

6) -6(-8 + n) = -54

42 - 6n = -54

-6n = -54 -52

6n = 106

n = 17.6

7) 3(x - 9) = -3

3x - 27 = -3

3x = 24

x = 8

8) 9k + 3 = -78

9k = -81

k = -9

9)4 + (n/4) = 8

By taking LCM,

16 + n/4 = 8

16 + n = 32

n = 16

10) -5r + 7 = -73

-5r = -80

r = 16

Hope it helps.

6 0

2 years ago

A ball is thrown vertically upward with an initial velocity of 48 feet per second. The distance s (in feet) of the ball from th

ra1l [238]

Hello,

s=48t-16t²

a)
s=0==>16t(3-t)=0==>t=0 or t=3

b)
s>32==>48t-16t²>32===>16(t²-3t+2)<0
Δ=9-8=1
==>16(t-1)(t-2)<0

==>1<t<2 (negative between the roots)

5 0

3 years ago